Many known processes that produce carbon dioxide gas (CO2), including Integrated Gasification Combined-Cycle systems (IGCC), are efficient and effective for producing needed power, chemicals, electricity, and other desirable products for modern society. However, there has been a widespread desire to capture the produced CO2 so that it does not emit this gas into the atmosphere. In recent years, there has been a growing concern related to gas emissions suspected of contributing to global climate change, particularly, CO2. Many jurisdictions are considering requirements for mitigation of CO2 being introduced into the atmosphere. Accordingly, there is a need to recover CO2 for sequestration or deposition as a product.
Many generally known systems for capturing such CO2 which have been under recent research and development include storage (e.g., underground) of the captured gas as a liquid, solid, or hydrate, or reuse for enhanced recovery of natural resources, e.g., enhanced oil recovery (EOR), or similar measures. Premier examples of systems that can provide power while also storing CO2 include many IGCC-CCS (carbon capture and storage) systems.
Some important sources of CO2, such as synthesis gas (“syngas”) produced by gasification or partial oxidation of carbonaceous fuels, also generate sulfide gases such as hydrogen sulfide (H2S), COS, or methyl mercaptan (CH3SH). It has already been proposed to recover CO2 from syngas (or syngas previously subjected to the water-gas shift reaction; shifted syngas), compress it, and store or send it to an EOR pipeline. Where CO2 and sulfide gases are co-generated, the sulfur component of the sulfide gases has mainly been recovered as elemental sulfur in a sulfur recovery unit (SRU).
In view of increasing desirability to capture and/or store CO2, it continues to be necessary to improve CO2 recovery systems so to maintain compliance with present and future environmental consideration and regulatory mandates.